U.S. patent number 11,273,839 [Application Number 16/247,093] was granted by the patent office on 2022-03-15 for vehicle control device.
This patent grant is currently assigned to TOYOTA JIDOSHA KABUSHIKI KAISHA. The grantee listed for this patent is TOYOTA JIDOSHA KABUSHIKI KAISHA. Invention is credited to Kenji Gotoda, Takahiro Komoda, Hiroki Kuwamoto.
United States Patent |
11,273,839 |
Komoda , et al. |
March 15, 2022 |
Vehicle control device
Abstract
A vehicle control device for a vehicle, the vehicle including a
rotation lock mechanism preventing rotation of a coupling portion
on the engine side of the rotating member in at least one
direction, and an engine rotation speed sensor detecting a rotation
speed of the engine, includes: a characteristic detecting portion
detecting at least a torsional rigidity as the rotational
characteristic by applying a torque to the rotating member from the
electric motor to measure a twist angle of the rotating member
while the rotation of the coupling portion is prevented by the
rotation lock mechanism; and an engine rotation filtering portion
calculating an actual resonance frequency based on the torsional
rigidity detected by the characteristic detecting portion and
filtering an engine rotation speed signal supplied from the engine
rotation speed sensor to attenuate a vibration component of the
actual resonance frequency in the engine rotation speed signal.
Inventors: |
Komoda; Takahiro (Nagoya,
JP), Gotoda; Kenji (Nagakute, JP),
Kuwamoto; Hiroki (Toyota, JP) |
Applicant: |
Name |
City |
State |
Country |
Type |
TOYOTA JIDOSHA KABUSHIKI KAISHA |
Toyota |
N/A |
JP |
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Assignee: |
TOYOTA JIDOSHA KABUSHIKI KAISHA
(Toyota, JP)
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Family
ID: |
1000006173032 |
Appl.
No.: |
16/247,093 |
Filed: |
January 14, 2019 |
Prior Publication Data
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Document
Identifier |
Publication Date |
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US 20190217852 A1 |
Jul 18, 2019 |
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Foreign Application Priority Data
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Jan 12, 2018 [JP] |
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JP2018-003740 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
B60W
10/08 (20130101); G01M 15/046 (20130101); B60W
50/00 (20130101); B60W 10/06 (20130101); G01M
15/11 (20130101); B60W 20/17 (20160101); B60W
2510/0638 (20130101); B60W 2710/081 (20130101); B60W
2050/0052 (20130101); G05D 16/02 (20130101); B60W
2030/206 (20130101) |
Current International
Class: |
B60W
50/00 (20060101); B60W 10/06 (20060101); G01M
15/11 (20060101); G01M 15/04 (20060101); B60W
10/08 (20060101); B60W 20/17 (20160101); B60W
30/20 (20060101); G05D 16/02 (20060101) |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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2009-144561 |
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Jul 2009 |
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JP |
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2016-107673 |
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Jun 2016 |
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JP |
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Primary Examiner: Ridley; Richard W
Assistant Examiner: Nguyen; Aimee T
Attorney, Agent or Firm: Oliff PLC
Claims
What is claimed is:
1. A vehicle control device for a vehicle including an engine, an
electric motor, and a rotating member disposed between the engine
and the electric motor with a rotational characteristic related to
an input torque, the vehicle including a rotation lock mechanism
preventing rotation of a coupling portion on the engine side of the
rotating member in at least one direction, and an engine rotation
speed sensor detecting a rotation speed of the engine, the vehicle
control device comprising: a characteristic detecting portion
detecting at least a torsional rigidity as the rotational
characteristic by applying a torque to the rotating member from the
electric motor to measure a twist angle of the rotating member
while the rotation of the coupling portion is prevented by the
rotation lock mechanism; and an engine rotation filtering portion
calculating an actual resonance frequency based on the torsional
rigidity detected by the characteristic detecting portion and
filtering an engine rotation speed signal supplied from the engine
rotation speed sensor to attenuate a vibration component of the
actual resonance frequency in the engine rotation speed signal.
2. The vehicle control device according to claim 1, comprising a
filter correcting portion making a correction based on a frequency
difference between the actual resonance frequency and a predefined
set resonance frequency for a reference filter characteristic
related to an attenuation frequency band and an attenuation gains
defined in advance depending on the set resonance frequency,
wherein the engine rotation filtering portion filters the engine
rotation speed signal in accordance with a corrected filter
characteristic which is obtained after the reference filter
characteristic is corrected by the filter correcting portion.
3. The vehicle control device according to claim 2, wherein when
the frequency difference between the actual resonance frequency and
the set resonance frequency is equal to or greater than a
predefined magnitude determination value, the filter correcting
portion corrects the attenuation frequency band of the reference
filter characteristic to move in a deviation direction of the
resonance frequency, and wherein when the frequency difference is
smaller than the magnitude determination value, the filter
correcting portion makes an emphasis correction by increasing the
attenuation gain of the reference filter characteristic and
narrowing the attenuation frequency band.
4. The vehicle control device according to claim 1, comprising an
abnormal-noise detecting portion making an abnormal noise
determination of a power transmission path based on a rotational
fluctuation in the engine rotation speed signal filtered by the
engine rotation filtering portion during operation of the
engine.
5. The vehicle control device according to claim 1, comprising a
misfire detecting portion making a misfire determination of the
engine based on a rotational fluctuation in the engine rotation
speed signal filtered by the engine rotation filtering portion
during operation of the engine.
6. The vehicle control device according to claim 1, comprising an
engine rotational drive portion providing a predefined control by
using the engine rotation speed signal filtered by the engine
rotation filtering portion when the engine is rotationally driven
via the rotating member by the electric motor.
7. The vehicle control device according to claim 2, comprising an
abnormal-noise detecting portion making an abnormal noise
determination of a power transmission path based on a rotational
fluctuation in the engine rotation speed signal filtered by the
engine rotation filtering portion during operation of the
engine.
8. The vehicle control device according to claim 2, comprising a
misfire detecting portion making a misfire determination of the
engine based on a rotational fluctuation in the engine rotation
speed signal filtered by the engine rotation filtering portion
during operation of the engine.
9. The vehicle control device according to claim 2, comprising an
engine rotational drive portion providing a predefined control by
using the engine rotation speed signal filtered by the engine
rotation filtering portion when the engine is rotationally driven
via the rotating member by the electric motor.
10. The vehicle control device according to claim 3, comprising an
abnormal-noise detecting portion making an abnormal noise
determination of a power transmission path based on a rotational
fluctuation in the engine rotation speed signal filtered by the
engine rotation filtering portion during operation of the
engine.
11. The vehicle control device according to claim 3, comprising a
misfire detecting portion making a misfire determination of the
engine based on a rotational fluctuation in the engine rotation
speed signal filtered by the engine rotation filtering portion
during operation of the engine.
12. The vehicle control device according to claim 3, comprising an
engine rotational drive portion providing a predefined control by
using the engine rotation speed signal filtered by the engine
rotation filtering portion when the engine is rotationally driven
via the rotating member by the electric motor.
13. A vehicle control device for a vehicle including an engine, an
electric motor, and a rotating member disposed between the engine
and the electric motor with a rotational characteristic related to
an input torque the vehicle including a rotation lock mechanism
preventing rotation of a coupling portion on the engine side of the
rotating member in at least one direction, and an engine rotation
speed sensor detecting a rotation speed of the engine, the vehicle
control device comprising: a characteristic detecting portion
detecting at least a torsional rigidity as the rotational
characteristic by applying a torque to the rotating member from the
electric motor to measure a twist angle of the rotating member
while the rotation of the coupling portion is prevented by the
rotation lock mechanism; and an electric motor rotational
fluctuation imparting portion calculating an actual resonance
frequency based on the torsional rigidity detected by the
characteristic detecting portion and periodically fluctuating a
target rotation speed of the electric motor depending on the actual
resonance frequency to suppress a rotational vibration of the
engine caused by the actual resonance frequency when the engine is
rotated via the rotating member by the electric motor.
14. The vehicle control device according to claim 13, comprising a
fluctuation characteristic correcting portion making a correction
based on a frequency difference between the actual resonance
frequency and a predefined set resonance frequency for a reference
fluctuation characteristic defined in advance depending on the set
resonance frequency in relation to an amplitude and a fluctuation
frequency band of a periodic fluctuation imparted to the target
rotation speed, wherein the electric motor rotational fluctuation
imparting portion periodically fluctuates the target rotation speed
in accordance with a fluctuation characteristic after the reference
fluctuation characteristic is corrected by the fluctuation
characteristic correcting portion.
15. The vehicle control device according to claim 14, wherein when
the frequency difference between the actual resonance frequency and
the set resonance frequency is equal to or greater than a
predefined magnitude determination value, the fluctuation
characteristic correcting portion corrects the fluctuation
frequency band of the reference fluctuation characteristic to move
in a deviation direction of the resonance frequency, and wherein
when the frequency difference is smaller than the magnitude
determination value, the fluctuation characteristic correcting
portion makes an emphasis correction by increasing the amplitude of
the reference fluctuation characteristic and narrowing the
fluctuation frequency band.
Description
The disclosure of Japanese Patent Application No. 2018-003740 filed
on Jan. 12, 2018 including the specification, drawings and abstract
is incorporated herein by reference in its entirety.
BACKGROUND OF THE INVENTION
Field of the Invention
The present invention relates to a vehicle control device and, more
particularly, to an improvement of a vehicle control device
providing various controls in consideration of rotational
characteristics of a rotating member such as a damper device.
Description of the Related Art
There is known a vehicle that includes an engine, an electric
motor, and a rotating member disposed between the engine and the
electric motor and having rotational characteristics related to an
input torque. For example, the rotating member is a damper device
absorbing rotational vibration of the engine or a power
transmission shaft having predetermined rigidity, and the
rotational characteristics are a rigidity value (torsional
rigidity) corresponding to a rate of a change in the input torque
to a change in twist angle, a hysteresis that is a difference in
the input torque when the twist angle increases and decreases, a
backlash dimension that is a change amount of the twist angle at
the time of reversal between positive and negative in the input
torque, etc. In some cases, power performance, vibration, noise,
etc. are affected by the rotational characteristics of the rotating
member. In Patent Document 1, to prevent resonance from occurring
in a vehicle due to rigidity of a damper device when an electric
motor is used as a drive power source for running, a technique is
proposed for changing a torque of the electric motor so as to
change the rigidity value of the damper device based on a
relationship (rotational characteristics) between the input torque
and the rigidity value of the damper device.
CITATION LIST
Patent Document 1: Japanese Laid-Open Patent Publication No.
2016-107673
SUMMARY OF THE INVENTION
Technical Problem
In a resonance frequency region determined depending on a torsional
rigidity of the rotating member, an engine rotation speed
accompanied by rotational vibration due to explosion etc. is
significantly vibrated due to resonance, and therefore, for
example, it is conceivable that a vibration component of a
resonance frequency is attenuated by a filter etc. from a signal
indicative of a detected engine rotation speed before the signal is
used for subsequent control. However, if the torsional rigidity
varies due to an individual difference, a temporal change, etc. of
the rotating member, the resonance frequency is changed so that the
vibration component attributable to resonance cannot properly be
attenuated from the engine rotation speed signal in some cases.
The present invention was conceived in view of the situations and
it is therefore an object of the present invention to provide an
engine rotation speed signal having a properly reduced vibration
component of a resonance frequency determined depending on a
torsional rigidity of a rotating member regardless of variations in
rotational characteristics (particularly torsional rigidity) due to
an individual difference, etc. of the rotating member.
Solution to Problem
To achieve the above object, a first aspect of the present
invention provides a vehicle control device for a vehicle including
an engine, an electric motor, and a rotating member disposed
between the engine and the electric motor with a rotational
characteristic related to an input torque, (a) the vehicle
including a rotation lock mechanism preventing rotation of a
coupling portion on the engine side of the rotating member in at
least one direction, and an engine rotation speed sensor detecting
a rotation speed of the engine, the vehicle control device
comprising: (b) a characteristic detecting portion detecting at
least a torsional rigidity as the rotational characteristic by
applying a torque to the rotating member from the electric motor to
measure a twist angle of the rotating member while the rotation of
the coupling portion is prevented by the rotation lock mechanism;
and (c) an engine rotation filtering portion calculating an actual
resonance frequency based on the torsional rigidity detected by the
characteristic detecting portion and filtering an engine rotation
speed signal supplied from the engine rotation speed sensor to
attenuate a vibration component of the actual resonance frequency
in the engine rotation speed signal.
A second aspect of the present invention provides the vehicle
control device recited in the first aspect of the invention,
comprising (a) a filter correcting portion making a correction
based on a frequency difference between the actual resonance
frequency and a predefined set resonance frequency for a reference
filter characteristic related to an attenuation frequency band and
an attenuation gains defined in advance depending on the set
resonance frequency, wherein (b) the engine rotation filtering
portion filters the engine rotation speed signal in accordance with
a corrected filter characteristic which is obtained after the
reference filter characteristic is corrected by the filter
correcting portion.
A third aspect of the present invention provides the vehicle
control device recited in the second aspect of the invention,
wherein when the frequency difference between the actual resonance
frequency and the set resonance frequency is equal to or greater
than a predefined magnitude determination value, the filter
correcting portion corrects the attenuation frequency band of the
reference filter characteristic to move in a deviation direction of
the resonance frequency, and wherein when the frequency difference
is smaller than the magnitude determination value, the filter
correcting portion makes an emphasis correction by increasing the
attenuation gain of the reference filter characteristic and
narrowing the attenuation frequency band.
A fourth aspect of the present invention provides the vehicle
control device recited in any one of the first to third aspects of
the invention, comprising an engine rotational drive portion
providing a predefined control by using the engine rotation speed
signal filtered by the engine rotation filtering portion when the
engine is rotationally driven via the rotating member by the
electric motor.
A fifth aspect of the present invention provides the vehicle
control device recited in any one of the first to third aspects of
the invention, comprising a misfire detecting portion making a
misfire determination of the engine based on a rotational
fluctuation in the engine rotation speed signal filtered by the
engine rotation filtering portion during operation of the
engine.
A sixth aspect of the present invention provides the vehicle
control device recited in any one of the first to third aspects of
the invention, comprising an abnormal-noise detecting portion
making an abnormal noise determination of a power transmission path
based on a rotational fluctuation in the engine rotation speed
signal filtered by the engine rotation filtering portion during
operation of the engine.
A seventh aspect of the present invention provides a vehicle
control device for a vehicle including an engine, an electric
motor, and a rotating member disposed between the engine and the
electric motor with a rotational characteristic related to an input
torque (a) the vehicle including a rotation lock mechanism
preventing rotation of a coupling portion on the engine side of the
rotating member in at least one direction, and an engine rotation
speed sensor detecting a rotation speed of the engine, the vehicle
control device comprising: (b) a characteristic detecting portion
detecting at least a torsional rigidity as the rotational
characteristic by applying a torque to the rotating member from the
electric motor to measure a twist angle of the rotating member
while the rotation of the coupling portion is prevented by the
rotation lock mechanism; and (c) an electric motor rotational
fluctuation imparting portion calculating an actual resonance
frequency based on the torsional rigidity detected by the
characteristic detecting portion and periodically fluctuating a
target rotation speed of the electric motor depending on the actual
resonance frequency to suppress a rotational vibration of the
engine caused by the actual resonance frequency when the engine is
rotated via the rotating member by the electric motor.
An eighth aspect of the present invention provides the vehicle
control device recited in the seventh aspect of the invention,
comprising (a) a fluctuation characteristic correcting portion
making a correction based on a frequency difference between the
actual resonance frequency and a predefined set resonance frequency
for a reference fluctuation characteristic defined in advance
depending on the set resonance frequency in relation to an
amplitude and a fluctuation frequency band of a periodic
fluctuation imparted to the target rotation speed, wherein (b) the
electric motor rotational fluctuation imparting portion
periodically fluctuates the target rotation speed in accordance
with a fluctuation characteristic after the reference fluctuation
characteristic is corrected by the fluctuation characteristic
correcting portion.
A ninth aspect of the present invention provides the vehicle
control device recited in the eighth aspect of the invention,
wherein when the frequency difference between the actual resonance
frequency and the set resonance frequency is equal to or greater
than a predefined magnitude determination value, the fluctuation
characteristic correcting portion corrects the fluctuation
frequency band of the reference fluctuation characteristic to move
in a deviation direction of the resonance frequency, and wherein
when the frequency difference is smaller than the magnitude
determination value, the fluctuation characteristic correcting
portion makes an emphasis correction by increasing the amplitude of
the reference fluctuation characteristic and narrowing the
fluctuation frequency band.
Advantageous Effects of Invention
In the vehicle control device as described above, the torsional
rigidity is detected by applying the torque to the rotating member
from the electric motor to measure the twist angle while the
rotation of the coupling portion on the engine side of the rotating
member is locked by the rotation lock mechanism, and the actual
resonance frequency is calculated based on the detected torsional
rigidity. Therefore, the actual resonance frequency can properly be
calculated based on the actual torsional rigidity regardless of
variations in torsional rigidity due to individual differences etc.
of the rotating member. The filtering is then performed, in the
first aspect of the invention, to attenuate the vibration component
of the actual resonance frequency in the engine rotation speed
signal, so that the vibration component attributable to resonance
is properly reduced in the obtained engine rotation speed signal.
Further, in the seventh aspect of the invention, when the engine is
rotated by the electric motor, the target rotation speed of the
electric motor is periodically fluctuated depending on the actual
resonance frequency to suppress the rotational vibration of the
engine caused by the actual resonance frequency, so that the
rotational vibration itself of the engine due to the resonance is
suppressed, and therefore, the vibration component attributable to
the resonance is properly reduced in the obtained engine rotation
speed signal. Therefore, in either case of the first aspect of the
present invention or the seventh aspect of the present invention,
the subsequent control using the engine rotation speed signal is
properly provided.
In the vehicle control device recited in the second aspect of the
invention, a correction is made based on the frequency difference
for the reference filter characteristic related to the attenuation
frequency band and the attenuation gain defined in advance
depending on the set resonance frequency, and the engine rotation
speed signal is filtered in accordance with the corrected filter
characteristic which is obtained after the correction, so that the
vibration component attributable to resonance is properly
reduced.
In the vehicle control device recited in the third aspect of the
invention, if the frequency difference is large, the attenuation
frequency band of the reference filter characteristic is corrected
to move in the deviation direction of the resonance frequency, so
that the vibration component attributable to resonance is properly
reduced from the engine rotation speed signal even if the frequency
difference is large. On the other hand, if the frequency difference
is small, the attenuation gain of the reference filter
characteristic is increased and the attenuation frequency band is
narrowed to make an emphasis correction, and therefore, only the
vibration component attributable to resonance can more properly be
reduced from the engine rotation speed signal.
The vehicle control device recited in the fourth aspect of the
invention provides a predefined control by using the filtered
engine rotation speed signal when the engine is rotationally driven
via the rotating member by the electric motor and therefore, the
engine rotation speed can highly accurately be controlled, or it
can highly accurately be determined that the engine rotation speed
has reached a predetermined determination value, without being
affected by the engine rotation vibration due to resonance, so that
the control using the engine rotation speed signal is properly
provided.
The vehicle control device recited in the fifth aspect of the
invention makes the misfire determination of the engine during the
operation of the engine based on the rotational fluctuation of the
engine rotation speed signal, wherein the determination is made by
using the filtered engine rotation speed, so that the misfire
determination is properly made with high accuracy without being
affected by engine rotational vibration due to resonance.
The vehicle control device recited in the sixth aspect of the
invention makes the abnormal noise determination of the power
transmission path during the operation of the engine based on the
rotational fluctuation of the engine rotation speed signal, wherein
the determination is made by using the filtered engine rotation
speed, so that the abnormal noise determination is properly made
with high accuracy without being affected by engine rotational
vibration due to resonance.
The vehicle control device recited in the eighth aspect of the
invention makes a correction based on the frequency difference for
the reference fluctuation characteristic related to the amplitude
and the fluctuation frequency band defined in advance depending on
the set resonance frequency, and the target rotation speed of the
electric motor is periodically fluctuated in accordance with the
fluctuation characteristic after the correction, so that the
rotational vibration itself of the engine due to resonance is
properly suppressed, and the vibration component attributable to
the resonance is properly reduced in the obtained engine rotation
speed signal.
In the vehicle control device recited in the ninth aspect of the
invention, if the frequency difference is relatively large, the
fluctuation frequency band of the reference fluctuation
characteristic is corrected to move in the deviation direction of
the resonance frequency, so that the rotational vibration of the
engine due to resonance is properly suppressed even if the
frequency difference is large. On the other hand, if the frequency
difference is small, the amplitude of the reference fluctuation
characteristic is increased and the fluctuation frequency band is
narrowed to make an emphasis correction, and therefore, the
rotational vibration of the engine due to resonance can more
properly be reduced.
BRIEF DESCRIPTION OF DRAWINGS
FIG. 1 is a skeleton diagram for explaining a drive system of a
hybrid vehicle to which the present invention is applied, showing
main portions of the control system together.
FIG. 2 is an example of a collinear chart of a differential
mechanism of the hybrid vehicle of FIG. 1.
FIG. 3 is a diagram of an example of a relationship between an
input torque Tin and a twist angle 1 of a damper device of FIG.
1.
FIG. 4 is a view illustrating rigidity values K1, K2, K3 obtained
from the relationship of FIG. 3.
FIG. 5 is an example of a time chart in the case that filtering is
performed to attenuate vibration of an engine rotation speed signal
SNe due to resonance when an engine is rotationally driven to
increase a rotation speed.
FIG. 6 is a flowchart specifically explaining a signal process
executed by a characteristic learning portion of FIG. 1.
FIG. 7 is a diagram of a principle of measuring the twist angle 1
while changing the input torque Tin of the damper device at steps
S4, S5 of FIG. 6.
FIG. 8 is a flowchart for explaining a filtering process of the
engine rotation speed signal SNe executed by a filter correcting
portion and an engine rotation filtering portion of FIG. 1.
FIG. 9 is a diagram for explaining an example of correction of a
reference filter characteristic (band-stop filter) for filtering
the engine rotation speed signal SNe when a frequency difference
.DELTA.fr is large at step F1-6 of FIG. 8.
FIG. 10 is a diagram for explaining an example of correction of a
reference filter characteristic (band-stop filter) for filtering
the engine rotation speed signal SNe when a frequency difference
.DELTA.fr is small at step F1-6 of FIG. 8.
FIG. 11 is a diagram for explaining an example of correction of a
reference filter characteristic (low-pass filter) different from
FIG. 9 when the frequency difference .DELTA.fr is large at step
F1-6 of FIG. 8.
FIG. 12 is a diagram for explaining an example of correction of a
reference filter characteristic (low-pass filter) different from
FIG. 10 when the frequency difference .DELTA.fr is small at step
F1-6 of FIG. 8.
FIG. 13 is a flowchart for explaining an operation (a signal
process) when an engine rotational drive portion of FIG. 1
rotationally drives the engine by using the engine rotation speed
signal SNe.
FIG. 14 is a flowchart for explaining an operation (a signal
process) when a misfire/abnormal-noise detecting portion of FIG. 1
makes a misfire determination of the engine and an abnormal noise
determination of a power transmission path based on the engine
rotation speed signal SNe.
FIG. 15 is a diagram for explaining another example of the present
invention and is a skeleton diagram of a hybrid vehicle
corresponding to FIG. 1.
FIG. 16 is a flowchart for explaining an operation (a signal
process) when a reference fluctuation characteristic defined in
advance by a fluctuation characteristic correcting portion of FIG.
15 is corrected by a fluctuation characteristic correcting portion
of FIG. 15 depending on an actual torsional rigidity of the damper
device.
FIG. 17 is a diagram for explaining an example of correction of a
reference fluctuation characteristic related to a periodic
fluctuation imparted to a target rotation speed Nmg1t of a first
motor generator when a frequency difference .DELTA.fr is large at
step F2-6 of FIG. 16.
FIG. 18 is a diagram for explaining an example of correction of a
reference fluctuation characteristic related to the periodic
fluctuation imparted to the target rotation speed Nmg1t of the
first motor generator when the frequency difference .DELTA.fr is
small at step F2-6 of FIG. 16.
FIG. 19 is a flowchart for explaining an operation (a signal
process) when an engine rotational drive portion of FIG. 15
rotationally drives the engine.
FIG. 20 is an example of a time chart showing changes in rotation
speed of portions when a rotational drive control of the engine is
provided in accordance with the flowchart of FIG. 19.
FIG. 21 is a diagram illustrating a case where a vibration
characteristic due to actual resonance is deviated by a variation
in torsional rigidity of the damper device with respect to a set
characteristic of a filter for attenuating a vibration component
attributable to resonance from an engine rotation speed signal.
FIG. 22 is a diagram for explaining a delay and a vibration of the
engine rotation speed signal SNe caused by deviation of the set
filter characteristic shown in FIG. 21.
DESCRIPTION OF THE PREFERRED EXAMPLES
The engine is an internal combustion engine generating power from
combustion of a fuel such as a gasoline engine and a diesel engine
and has a rotational vibration occurring due to explosion etc., and
the rotational vibration may be amplified by resonance of a
rotating member having a torsional rigidity such as a damper
device. For the electric motor, a motor generator also usable as an
electric generator is suitably used. The rotating member having
rotational characteristics for an input torque is a damper device
absorbing rotational vibration of the engine or a power
transmission shaft having predetermined torsional rigidity, for
example. The damper device includes an elastic body such as a
spring and a friction mechanism, for example, or may include only
the elastic body. The rotational characteristics for an input
torque of the rotating member are a rigidity value of torsional
rigidity corresponding to a rate of a change in the input torque to
a change in twist angle, a hysteresis that is a difference in the
input torque when the twist angle increases and decreases, a
backlash dimension that is a change amount of the twist angle at
the time of reversal between positive and negative in the input
torque, etc., and at least include the torsional rigidity. Although
the rigidity value is appropriate for the torsional rigidity, other
physical quantities corresponding to the rigidity value may also be
used.
For the rotation lock mechanism preventing rotation of the coupling
portion on the engine side of the rotating member in the at least
one direction, a friction brake of a hydraulic type etc., a meshing
brake, or a one-way clutch etc. is suitably used. In the case of
the one-way clutch, for example, the one-way clutch is disposed to
prevent the rotation in a reverse rotation direction of the engine,
otherwise, when power transmission between the engine and the
rotating member is interrupted by a clutch etc., the rotation may
be prevented in one arbitrary direction. The characteristic
detecting portion detecting the rotational characteristics of the
rotating member desirably detects the characteristic, for example,
while the vehicle is stopped with the engine stopped and a vehicle
speed being zero or can detect the characteristic during motor
running while the second electric motor is used as the drive power
source for running with the engine stopped. The detection may
simply be executed at the time of vehicle inspection and the
detected characteristic may be stored or may periodically be
executed and updated (learned) based on a predetermined running
distance or a running time and the detected characteristic may be
successively replaced or used for learning, and other various forms
are available. If temporal changes have a large influence, it is
desirable to execute the learning periodically based on certain
conditions.
If a drive power is generated when the rotational characteristics
are detected, it is desirable to control the torque of the second
electric motor usable as a drive power source to offset the drive
power; however, in the case of detection of the rotational
characteristics during stop of the vehicle, for example, the
detection may be performed on condition that a depressing operation
of a brake is performed, that a shift lever is operated to a P
(parking) position to put a parking gear into an engaged state, or
that a parking brake is in operation. If the vehicle includes an
automatic brake system which automatically controls a brake force
of a wheel brake, the wheel brake may be actuated. If a drive power
fluctuation including that detected during running of the vehicle
is slight, or in the case of the detection before the shipment of
the vehicle or during vehicle inspecting, the offset control of the
drive power may be omitted. The offset control may not necessarily
completely eliminate the drive power fluctuation, and the drive
power fluctuation is may be reduced.
The present invention is applied to, for example, a vehicle having
a differential mechanism distributing an output of an engine to an
electric motor and a driving wheel side and may be applied to
various vehicles such as a vehicle having an engine and an electric
motor connected in series across a rotating member such as a damper
device and a vehicle transmitting outputs of an engine and an
electric motor combined by a planetary gear device etc. toward
driving wheels. A transmission gear and a connecting/disconnecting
device such as a clutch etc. may be disposed as needed between the
engine and the rotating member as well as between the rotating
member and the electric motor. If the engine and the rotating
member are directly coupled via a coupling shaft etc., the rotation
in at least one direction prevented by the rotation lock mechanism
is determined such that reverse rotation of the engine is
prevented, and the characteristic detecting portion applies a
torque in the reverse rotation direction to the rotating member;
however, if the connecting/disconnecting device is disposed between
the engine and the rotating member, the direction of the rotation
of the rotating member to be prevented is not particularly limited.
If rotation is prevented in both directions by the rotation lock
mechanism, the direction of the torque applied to the rotating
member is not necessarily limited at the time of the detection by
the characteristic detecting portion. The rotational
characteristics can be obtained also by changing the torque in both
positive and negative directions.
The engine rotation filtering portion and the electric motor
rotational fluctuation imparting portion can calculate an actual
resonance frequency in accordance with a map, arithmetic
expression, etc. defined in advance based on the torsional rigidity
and an inertia moment detected by the characteristic detecting
portion, for example. The inertia moment is set in advance based on
the mass and size of the engine, the rotating member, and a
flywheel, for example. The engine rotation filtering portion is
configured to correct a filter characteristic of filtering of the
engine rotation speed signal, for example, a reference filter
characteristic determined in advance depending on a set resonance
frequency, based on the frequency difference between the actual
resonance frequency and the set resonance frequency; however, the
filter characteristic can be selected or set based only on the
actual resonance frequency. When the reference filter
characteristic is corrected based on the frequency difference
between the actual resonance frequency and the set resonance
frequency, the form of correction can be changed depending on the
magnitude of the frequency difference; however, the correction can
always be made in a constant form regardless of the magnitude of
the frequency difference and, for example, the attenuation
frequency band may merely be shifted depending on the frequency
difference, or both the attenuation gain and the attenuation
frequency band may be changed depending on the frequency
difference, and various other forms are available.
For example, when the engine is rotationally driven and cranked by
the electric motor at the start of the engine, the engine rotation
speed signal filtered by the engine rotation filtering portion is
suitably used when it is determined whether a termination
determination value for terminating the cranking has been reached
or when a determination is made on misfire of the engine or on an
abnormal noise of a power transmission path (an engine state in
which abnormal noise is generated) based on the rotational
fluctuation of the engine rotation speed signal during operation of
the engine. The filtered engine rotation speed signal can also be
used for various engine-related controls for providing a control
based on the engine rotation speed, a control using the engine
rotation speed, etc. when the engine rotation speed is changed
across a resonance frequency band of the rotating member or when
the engine is operated in the vicinity of the resonance frequency
band, for example. The attenuation frequency band and the
attenuation gain of the filter characteristic for filtering the
engine rotation speed signal are individually appropriately
determined depending on a purpose of use etc. of the engine
rotation speed signal, or the engine rotation speed signal filtered
with the same filter characteristic may be usable in multiple
controls.
The electric motor rotational fluctuation imparting portion is
configured to correct a fluctuation characteristic of a periodic
fluctuation imparted to the target rotation speed of the electric
motor, for example, a reference fluctuation characteristic
determined in advance depending on the set resonance frequency,
based on the frequency difference between the actual resonance
frequency and the set resonance frequency; however, the fluctuation
characteristic can be selected or set based only on the actual
resonance frequency. When the reference fluctuation characteristic
is corrected based on the frequency difference between the actual
resonance frequency and the set resonance frequency, the form of
correction can be changed depending on the magnitude of the
frequency difference; however, the correction can always be made in
a constant form regardless of the magnitude of the frequency
difference and, for example, the fluctuation frequency band may
merely be shifted depending on the frequency difference, or both
the amplitude and the fluctuation frequency band may be changed
depending on the frequency difference, and various other forms are
available.
The present invention is suitably applied to, for example, a hybrid
vehicle that includes a differential mechanism distributing the
output of the engine to the electric motor and the driving wheel
side and a damper device disposed as the rotating member between
the engine and the differential mechanism and that can use the
engine as the drive power source for running through the torque
control of the electric motor and is also applicable to a series
hybrid vehicle in which the engine is exclusively used for
rotationally driving an electric generator to generate electricity.
In such a hybrid vehicle, for example, a second electric motor
usable as a drive power source is disposed as needed in a power
transmission path between the differential mechanism and the
driving wheels or at another power transmission position.
EXAMPLE
An example of the present invention will now be described in detail
below with reference to the drawings.
FIG. 1 is a skeleton diagram for explaining a drive system of a
hybrid vehicle 10 to which the present invention is applied,
showing main portions of the control system together. The hybrid
vehicle 10 has, for example, a transversely-mounted drive system of
an FF (front-engine front-wheel drive) type etc. and includes in a
power transmission path between an engine 12 and a pair of left and
right driving wheels 14, a first drive portion 16, a second drive
portion 18, a final reduction gear 20, a pair of left and right
axles 22, etc. The engine 12 is an internal combustion engine such
as a gasoline engine and a diesel engine and has a crankshaft 24 to
which a damper device 26 absorbing a torque fluctuation is coupled.
The damper device 26 includes a first rotating element 26a coupled
to the crankshaft 24 and a second rotating element 26b coupled via
an input shaft 28 to a differential mechanism 30 with multiple
types of springs 32 and a friction mechanism 34 interposed between
the first rotating element 26a and the second rotating element 26b,
so that a rigidity value (spring constant) corresponding to a rate
of a change in input torque Tin to a change in twist angle 1 is
changed stepwise. A torque limiter 35 is disposed on an outer
circumferential end portion of the damper device 26. The damper
device 26 corresponds to a rotating member having rotational
characteristics related to the input torque Tin, and the first
rotating element 26a corresponds to a coupling portion of the
damper device 26 on the engine 12 side.
The crankshaft 24 integrally coupled to the first rotating element
26a is coupled to a housing 38 via a meshing brake 36 so that
rotation is prevented. The meshing brake 36 has meshing teeth 24a
disposed on the crankshaft 24, meshing teeth 38a disposed on the
housing 38, and a meshing sleeve 36a having an inner
circumferential surface provided with meshing teeth capable of
meshing simultaneously with both the meshing teeth 24a, 38a, and
the meshing sleeve 36a is moved in an axial direction so that the
crankshaft 24 is switched between a state in which the crankshaft
24 is relatively non-rotatably engaged with the housing 38 and a
state in which the crankshaft 24 is released from the housing 38
and made freely rotatable. For example, an electromagnetic
switching valve etc. disposed in a hydraulic control circuit 58 is
switched in accordance with a hydraulic control signal Sac supplied
from an electronic control device 90, so that the meshing sleeve
36a is moved in the axial direction via a hydraulic cylinder etc.
to engage and release the meshing brake 36. Alternatively, the
meshing sleeve 36a can be moved in the axial direction by using
another drive device such as an electric feed screw mechanism. The
meshing brake 36 is provided with a synchronizing mechanism of a
cone type etc. as needed. The meshing brake 36 corresponds to a
rotation lock mechanism, and instead of the meshing brake 36, a
friction brake or a one-way clutch which prevents the engine 12
from rotating in only the reverse rotation direction can be
employed as the rotation lock mechanism. An engine
connecting/disconnecting clutch capable of enabling/disenabling
power transmission can be disposed between the engine 12 and the
meshing teeth 24a.
The first drive portion 16 is configured to include a first motor
generator MG1 and an output gear 40 in addition to the engine 12,
the differential mechanism 30, and the meshing brake 36. The
differential mechanism 30 is a single pinion type planetary gear
device and includes a sun gear S, a ring gear R, and a carrier CA
as three rotating elements in a differentially rotatable manner;
the first motor generator MG1 is coupled to the sun gear S; the
input shaft 28 is coupled to the carrier CA; and the output gear 40
is coupled to the ring gear R. Therefore, a torque transmitted from
the engine 12 via the damper device 26 to the carrier CA of the
differential mechanism 30 is distributed by the differential
mechanism 30 to the first motor generator MG1 and the output gear
40, and when a rotation speed (MG1 rotation speed) Nmg1 of the
first motor generator MG1 is controlled through regenerative
control etc., a rotation speed (engine rotation speed) Ne of the
engine 12 is continuously variably changed and output from the
output gear 40. Therefore, the differential mechanism 30 and the
first motor generator MG1 function as an electric continuously
variable transmission. The first motor generator MG1 alternatively
functions as an electric motor or an electric generator and is
connected through an inverter 60 to an electric storage device 62
such as a battery.
On the other hand, when the first motor generator MG1 is
rotationally driven in a negative rotation direction opposite to a
running direction of the engine 12 while the rotation of the
crankshaft 24 is prevented by the meshing brake 36, i.e., while a
rotation of the carrier CA is prevented via the damper device 26, a
torque is applied to the output gear 40 in the positive rotation
direction (vehicle forward direction) same as the running direction
of the engine 12 due to a reaction force generated by the meshing
brake 36, and the output gear 40 is rotationally driven in the
positive rotation direction. When the first motor generator MG1 is
rotationally driven in the positive rotation direction same as the
running direction of the engine 12, a torque is applied to the
output gear 40 in the reverse rotation direction (vehicle reverse
direction) opposite to the running direction of the engine 12 due
to a reaction force generated by the meshing brake 36, and the
output gear 40 is rotationally driven in the reverse rotation
direction. In such a case, a torque of the first motor generator
MG1 is amplified depending on a gear ratio .rho. of the
differential mechanism 30 and applied to the damper device 26
coupled to the carrier CA. The first motor generator MG1 is an
electric motor capable of applying a torque to the damper device 26
via the differential mechanism 30.
FIG. 2 is a collinear chart in which the three rotating elements of
the differential mechanism 30, i.e., the sun gear S, the ring gear
R, and the carrier CA, can be connected by a straight line in terms
of rotation speed; the upward direction of FIG. 2 is the running
direction of the engine 12, i.e., the positive rotation direction;
and an intervals among the vertical axes are determined depending
on the gear ratio .rho. (=the number of teeth of the sun gear S/the
number of teeth of the ring gear R) of the differential mechanism
30. For example, describing a case that the output gear 40 is
rotationally driven in the vehicle forward direction by the first
motor generator MG1, a torque of rotation in the negative rotation
direction (the downward direction of FIG. 2) opposite to the
running direction of the engine 12 is applied to the sun gear S as
indicated by an arrow P1 through a power running control of the
first motor generator MG1 while the rotation of the carrier CA is
prevented by the meshing brake 36, and when the sun gear S is
rotationally driven in the negative rotation direction, a torque of
rotation in the positive rotation direction (the upward direction
of FIG. 2) same as the running direction of the engine 12 is
applied as indicated by an arrow P2 to the ring gear R to which the
output gear 40 is coupled, so that a drive power is obtained in the
forward direction.
Returning to FIG. 1, the output gear 40 is meshed with a large
diameter gear 44 disposed on an intermediate shaft 42 parallel to
the input shaft 28. A dog clutch 43 is disposed between the large
diameter gear 44 and the intermediate shaft 42 so that a power
transmission is selectively switched between to be enabled and
disenabled. This dog clutch 43 is configured in the same way as the
meshing brake 36 and has an engaged state and a disengaged state
switched therebetween via a hydraulic cylinder etc. when another
electromagnetic switching valve etc. disposed in the hydraulic
control circuit 58 is switched in accordance with the hydraulic
control signal Sac supplied from the electronic control device 90,
so that the power transmission is enabled and disenabled between
the large diameter gear 44 and the intermediate shaft 42. A small
diameter gear 46 smaller in diameter than the large diameter gear
44 is disposed on the intermediate shaft 42, and the small diameter
gear 46 is meshed with a differential ring gear 48 of the final
reduction gear 20. Therefore, the rotation of the output gear 40 is
reduced in speed depending on a ratio of the number of teeth
between the output gear 40 and the large diameter gear 44 and a
ratio of the numbers of teeth between the small diameter gear 46
and the differential ring gear 48 and transmitted to the final
reduction gear 20 and is further transmitted from the pair of the
axles 22 to the driving wheels 14 through a differential gear
mechanism of the final reduction gear 20. A parking gear 45 is
relatively non-rotatably disposed on the intermediate shaft 42, and
when a parking range is selected by operation of a shift lever to a
P position for parking etc., a parking lock pawl not shown is
pressed against and meshed with the parking gear 45 in accordance
with an urging force of a spring etc. so as to prevent rotation of
members on the driving wheel 14 side from the intermediate shaft
42.
The second drive portion 18 is configured to include a second motor
generator MG2 and a motor output gear 52 disposed on a motor shaft
50 of the second motor generator MG2, and the motor output gear 52
is meshed with the large diameter gear 44. Therefore, a rotation
speed (MG2 rotation speed Nmg2) of the second motor generator MG2
is reduced depending on a ratio of the number of teeth between the
motor output gear 52 and the large diameter gear 44 and a ratio of
the number of teeth between the small diameter gear 46 and the
differential ring gear 48 and transmitted to the final reduction
gear 20 to rotationally drive the driving wheels 14 via the pair of
the axles 22. The second motor generator MG2 alternatively
functions as an electric motor and an electric generator and is
connected through the inverter 60 to the electric storage device
62. The second motor generator MG2 corresponds to a second electric
motor usable as a drive power source.
The hybrid vehicle 10 also includes an automatic brake system 66.
The automatic brake system 66 electrically controls a brake force
i.e. a brake hydraulic pressure, of each of wheel brakes 67
disposed on the driving wheels 14 and driven wheels (non-driving
wheels) not shown in accordance with a brake control signal Sb
supplied from the electronic control device 90. The wheel brake 67
is also supplied with a brake hydraulic pressure via a brake master
cylinder when a brake pedal not shown is depressed, so that a brake
force is mechanically generated depending on the brake hydraulic
pressure, i.e., a brake operating force.
The hybrid vehicle 10 having the drive system configured as
described above includes the electronic control device 90 as a
controller providing various controls such as an output control of
the engine 12, a torque control of the motor generators MG1, MG2,
an engagement/release control of the meshing brake 36 and the dog
clutch 43, a control of automatic braking by the automatic brake
system 66. The electronic control device 90 includes a so-called
microcomputer having a CPU, a RAM, a ROM, an input/output
interface, etc. and executes a signal process according to a
program stored in advance in the ROM, while utilizing a temporary
storage function of the RAM to provide the various controls. The
electronic control device 90 is supplied with signals indicative of
various pieces of information required for control such as the
engine rotation speed Ne, a vehicle speed V, the MG1 rotation speed
Nmg1, the MG2 rotation speed Nmg2, an accelerator operation amount
(accelerator pedal depression operation amount) Acc, a shift lever
operation position Psh, and an electric storage remaining amount
SOC of the electric storage device 62, from an engine rotation
speed sensor 70, a vehicle speed sensor 72, an MG1 rotation speed
sensor 74, an MG2 rotation speed sensor 76, an accelerator
operation amount sensor 78, a shift position sensor 80, and an SOC
sensor 64, respectively, for example. Examples of the shift lever
operation position Psh include a D position for forward running, an
R position for reverse running, the P position for parking, and an
N position for neutral, and when the parking range is selected by
operation to the P position, the parking lock pawl is meshed with
the parking gear 45 disposed on the intermediate shaft 42 so that
rotation of the parking gear 45 is mechanically prevented. The
electronic control device 90 outputs, for example, an engine
control signal Se for controlling an engine output through an
electronic throttle valve, a fuel injection device, an ignition
device, etc. of the engine 12, a motor control signal Sm for
controlling torques (power running torque and regenerative torque)
of the motor generators MG1 and MG2, the hydraulic control signal
Sac switching the meshing brake 36 and the dog clutch 43 between
engaged and disengaged states via the electromagnetic switching
valve etc. of the hydraulic control circuit 58, and the brake
control signal Sb controlling the brake force of the wheel brake 67
via the automatic brake system 66.
The damper device 26 has a relationship between the input torque
Tin and the twist angle .PHI., for example, as shown in FIG. 3, due
to the action of the springs 32 and the friction mechanism 34 etc.
Although FIG. 3 shows a symmetric change with respect to an origin
O, the damper device 26 causing an asymmetric change is also
employable. From the relationship between the input torque Tin and
the twist angle .PHI., the rotational characteristic related to the
torsional rigidity can be identified as shown in FIG. 4. The
torsional rigidity is a change characteristic of the input torque
Tin with respect to the twist angle .PHI. and has three kinds K1,
K2, K3 of a rigidity value corresponding to a rate of a change
.DELTA.Tin of the input torque Tin to a change .DELTA..PHI. of the
twist angle .PHI., i.e., .DELTA.Tin/.DELTA..PHI., and the rigidity
value changes at two change points A1, A2 different in the input
torque Tin. Therefore, the rigidity value is K1 in a region of the
input torque Tin equal to or less than A1, the rigidity value is K2
in a region from A1 to A2, and the rigidity value is K3 in a region
greater than A2. The damper device 26 resonates in a predetermined
frequency region determined depending on the rigidity values K1 to
K3.
On the other hand, the engine 12 has rotational vibration generated
by explosion etc., and the rotational vibration is amplified by
resonance in the vicinity of the resonance frequency determined
depending on the rigidity values K1 to K3 of the damper device 26.
Therefore, an engine rotation speed signal SNe indicative of the
engine rotation speed Ne detected by the engine rotation speed
sensor 70 also includes vibration, and when various controls are
provided by using the engine rotation speed signal SNe, a control
accuracy may be impaired by the vibration. In this regard, it is
conceivable that the engine rotation speed signal SNe is filtered
depending on the torsional rigidity of the damper device 26 so as
to attenuate a vibration component of the resonance frequency. FIG.
5 is an example of a time chart of the engine rotation speed signal
SNe when the engine 12 is rotationally driven via the damper device
26 by the first motor generator MG1 to increase the engine rotation
speed Ne. Since the engine rotation speed Ne has the vibration
(pulsation) caused by resonance in the resonance frequency region
of the damper device 26, the engine rotation speed signal SNe
supplied from the engine rotation speed sensor 70 also has
vibration as indicated by a solid line of FIG. 5; however, the
signal SNe can be smoothed as indicated by a broken line of FIG. 5
by filtering determined depending on the torsional rigidity of the
damper device 26 so as to attenuate the vibration due to
resonance.
However, the rotational characteristics of the damper device 26,
i.e., the rigidity values K1 to K3 and the change points A1, A2
related to the torsional rigidity, may vary due to individual
differences of the damper device 26, i.e., dimensional errors of
component parts and variations in spring constant of the springs
32, variations in friction coefficient of friction material of the
friction mechanism 34, etc., and may change due to a temporal
change. When the torsional rigidity varies as described above, the
resonance frequency is changed so that the vibration component
attributable to the resonance cannot properly be attenuated from
the engine rotation speed signal SNe. Specifically describing with
reference to FIGS. 21 and 22, a solid line of FIG. 21 is an example
of a filter characteristic preset for filtering for attenuating the
vibration component of the resonance frequency, and if a vibration
characteristic of the rotational vibration caused by the actual
resonance is deviated as indicated by a broken line of FIG. 21 from
this set filter characteristic, an excessive portion E1 and an
insufficient portion E2 are generated. If the excessive portion E1
and the insufficient portion E2 are generated as described above,
the engine rotation speed signal SNe has a delay attributable to
the excessive portion E1 as indicated by a solid line of FIG. 22
and has a remaining rotational vibration due to the insufficient
portion E2. Therefore, the subsequent control using the engine
rotation speed signal SNe may not properly be provided. A broken
line of FIG. 22 indicates the engine rotation speed signal SNe when
the vibration characteristic of the actual resonance substantially
coincides with the set filter characteristic and the rotational
vibration due to resonance is properly attenuated by filtering.
In this regard, the electronic control device 90 functionally
includes a characteristic learning portion 92, a characteristic
storage portion 94, and an engine-related control portion 96 and
can filter the engine rotation speed signal SNe based on the actual
torsional rigidity of the damper device 26 so as to provide various
controls by using the engine rotation speed signal SNe with the
rotational vibration due to resonance properly attenuated. The
electronic control device 90 corresponds to a vehicle control
device.
The characteristic learning portion 92 provides a learning control
in accordance with steps S1 to S13 (hereinafter simply referred to
as S1 to S13; steps are omitted also in the other flowcharts) of a
flowchart of FIG. 6. This learning control is periodically provided
under certain conditions determined based on a running distance or
a running time of the hybrid vehicle 10 in this example. At S1, it
is determined whether the engine 12 is stopped, and if the engine
12 is in a stop state, S2 is executed, or if the engine 12 is in
operation, the control is terminated. At S2, it is determined
whether a predefined learning prohibition condition is satisfied.
For the learning prohibition condition, for example, (a) and (b)
are defined as follows.
(a) The electric storage remaining amount SOC of the electric
storage device 62 is equal to or less than a lower limit value
defined in advance for ensuring restarting of the engine 12
etc.
(b) An engine start request is made (an air conditioning request, a
driver's accelerator operation, etc.).
If any one of the learning prohibition conditions is satisfied, the
control is terminated, and if none is satisfied, learning is
possible, so that S3 and subsequent steps are executed. At S3, it
is determined whether the hybrid vehicle 10 is in a stop state,
i.e., whether the vehicle speed V is 0, and if the vehicle 10 is in
the stop state, S4 and subsequent steps are executed. At S4, the
meshing brake 36 is engaged to lock the crankshaft 24 in a
non-rotatable manner, and at S5, the first motor generator MG1 is
subjected to the power running control so that the torque (the
input torque Tin) is applied to the damper device 26 to measure the
twist angle .PHI.. FIG. 7 is a diagram for explaining a principle
of applying the input torque Tin and measuring the twist angle 1 in
this way, and the relationship as shown in FIG. 3 can be obtained
by providing the power running control of the first motor generator
MG1 to apply the torque (the input torque Tin) to the damper device
26 via the differential mechanism 30 while the meshing brake 36 is
engaged to lock the crankshaft 24. Specifically, by measuring the
MG1 rotation speed Nmg1 with the MG1 rotation speed sensor 74 such
as a resolver while continuously increasing and decreasing the
torque of the first motor generator MG1, the relationship between
the input torque Tin and the twist angle 1 as shown in FIG. 3 can
be obtained. Based on the gear ratio .rho. of the differential
mechanism 30, the input torque Tin can be calculated from the motor
torque of the first motor generator MG1, and the twist angle 1 can
be calculated from the MG1 rotation speed Nmg1. Since the
relationship between the input torque Tin and the twist angle .PHI.
of the damper device 26 of this example symmetrically changes with
respect to the origin O as shown in FIG. 3, only one of the
positive and negative regions may be measured. If a one-way clutch
is disposed instead of the meshing brake 36 to prevent the rotation
of the engine 12 only in the reverse rotation direction, the twist
angle .PHI. may be measured such that the torque in the reverse
rotation direction is applied as the input torque Tin.
S6 is executed concurrently with the execution of S5 to suppress
the behavior of the vehicle 10 such that the vehicle 10 is retained
in the stop state regardless of the power running control of the
first motor generator MG1. Specifically, when a torque is applied
to the damper device 26 by providing the power running control of
the first motor generator MG1, a torque is transmitted to the
output gear 40 due to a reaction force thereof so that a drive
power is generated, and therefore, the behavior of the vehicle 10
caused by the drive power is restrained. More specifically, for
example, if the parking range is selected and the parking lock pawl
is urged to mesh with the parking gear 45, the second motor
generator MG2 is subjected to the power running control to slightly
rotate the intermediate shaft 42, and the parking lock pawl is
thereby reliably meshed with the parking gear 45. For another
means, a brake force may be generated in the wheel brake 67 by the
automatic brake system 66. Alternatively, the dog clutch 43 is
released to interrupt the power transmission toward the driving
wheel 14 while a torque of the second motor generator MG2 is
controlled to prevent the rotation of the output gear 40 so that a
predetermined input torque Tin is applied to the damper device 26.
In other words, the torque of the second motor generator MG2 is
controlled to offset the drive power generated by the power running
control of the first motor generator MG1, and this control can be
provided even while the dog clutch 43 is engaged and is also
applicable to a vehicle without the dog clutch 43. When the parking
range is selected, the parking lock pawl is engaged with the
parking gear 45 to prevent the rotation of the driving wheels 14,
so that the vehicle behavior restraining control of S6 may be
omitted.
When the determination of S3 is NO (negative), i.e., when the
vehicle 10 is running rather than being in the stop state, S7 to S9
are executed to obtain the relationship between the input torque
Tin and the twist angle .PHI.. Specifically, at S7 and S8, as in S4
and S5, while the crankshaft 24 is non-rotatably locked by the
meshing brake 36, the first motor generator MG1 is subjected to the
power running control so that the torque (the input torque Tin) is
applied to the damper device 26 to measure the twist angle .PHI..
In this case, as shown in FIG. 2, the output gear 40 is rotated
depending on the vehicle speed V, and the first motor generator MG1
is further rotated in the reverse rotation direction, so that the
twist angle 1 is calculated by subtracting an amount corresponding
to the rotation speed of the first motor generator MG1. During
running in two-motor drive mode in which the first motor generator
MG1 is also used as a drive power source, the two-motor drive is
once switched to single-motor drive in which only the second motor
generator MG2 is used as the drive power source, and the twist
angle .PHI. can thereby be measured with the MG1 rotation speed
sensor 74 such as a resolver while continuously increasing and
decreasing the torque of the first motor generator MG1. At S9, the
torque of the second motor generator MG2 is controlled to increase
or decrease so as to offset the drive power generated by the power
running control of the first motor generator MG1, and a change in
drive power of the vehicle 10 is thereby suppressed. When the
hybrid vehicle 10 is coasting, the dog clutch 43 may be released to
interrupt the power transmission toward the driving wheels 14, and
the torque of the second motor generator MG2 may be controlled to
offset the drive power generated by the power running control of
the first motor generator MG1. Even during running with a
predetermined drive power, similarly, while the dog clutch 43 is
released to interrupt the power transmission toward the driving
wheels 14, the torque of the second motor generator MG2 may be
controlled to offset the drive power generated by the power running
control of the first motor generator MG1.
At S10 following S6 or S9, it is determined whether a predefined
learning stop condition is satisfied. For the learning stop
condition, for example, (a) to (g) are defined as follows.
(a) The electric storage remaining amount SOC of the electric
storage device 62 is equal to or less than a lower limit value
defined in advance for ensuring the startability of the engine 12
etc.
(b) An engine start request is made (an air conditioning request, a
driver's accelerator operation, etc.).
(c) The vehicle is in a condition causing resonance (a surging
torque input to tires, an uneven road, etc.).
(d) The drive power becomes insufficient (a slope, a high drive
power, etc.).
(e) A motor torque must be generated for other requirements (a
motor torque for eliminating a backlash or starting an engine,
etc.).
(f) The motor is in a low rotation speed region (i.e., the vehicle
is in a low vehicle speed region) in which a motor cogging torque
is large.
(g) The vehicle is moving at the time of measurement for the
vehicle stop state.
If any one of the learning stop conditions is satisfied, the
learning control is stopped and terminated at S13, and if none is
satisfied, S11 is executed. At S11, it is determined whether a
series of measurements according to execution of S5 or S8 is
completed, and 510 is repeatedly executed until the series of
measurements are completed. If the series of measurements are
completed without satisfying the learning stop condition of S10,
the determination at S11 is YES (affirmative), and S12 is executed
to identify and store (overwrite) the rotational characteristics of
the damper device 26 in the characteristic storage portion 94.
Specifically, from the relationship between the input torque Tin
and the twist angle .PHI. as shown in FIG. 3 obtained by executing
S5 or S8, at least the rigidity values K1 to K3 shown in FIG. 4 are
extracted, and the rigidity values K1 to K3 are stored in the
characteristic storage portion 94. As a result, the engine-related
control portion 96 can filter the engine rotation speed signal SNe
based on the new rigidity values K1 to K3 stored in the
characteristic storage portion 94 so as to provide various controls
by using the engine rotation speed signal SNe with the rotational
vibration due to resonance attenuated.
The engine-related control portion 96 provides various controls by
using the engine rotation speed signal SNe and specifically
functionally includes an engine rotational drive portion 100 and a
misfire/abnormal-noise detecting portion 110. To attenuate the
vibration component attributable to the resonance of the damper
device 26 from the engine rotation speed signal SNe supplied from
the engine rotation speed sensor 70, the engine rotational drive
portion 100 and the misfire/abnormal-noise detecting portion 110
respectively include filter correcting portions 102, 112 and engine
rotation filtering portions 104, 114. FIG. 8 is a flowchart for
specifically explaining a signal process by the filter correcting
portions 102, 112 and the engine rotation filtering portions 104,
114, and F1-1 to F1-6 correspond to the filter correcting portions
102, 112, while F1-7 to F1-9 correspond to the engine rotation
filtering portions 104, 114. Since the filtering of the engine
rotation speed signal SNe in the engine rotational drive portion
100 and the misfire/abnormal-noise detecting portion 110 differs
only in filtering characteristics at the time of filtering, it will
be described with reference to a common flowchart.
At F1-1 of FIG. 8, an inertia moment M necessary for calculating an
actual resonance frequency fr of the damper device 26 is read. The
inertia moment M is preliminarily set to a constant value based on
the mass, size, etc. of the engine 12, the damper device 26, a
flywheel, etc. At F1-2, an initially-set reference filter
characteristic Fp is read. The reference filter characteristic Fp
is used for attenuating only a frequency component of rotational
fluctuation attributable to resonance from an engine rotation speed
signal SNe through filtering, is set based on a set resonance
frequency fro defined in advance, and is defined as indicated by
solid lines in FIGS. 9 to 12 in terms of an attenuation frequency
band defined to include the set resonance frequency fro and an
attenuation gain Go in the attenuation frequency band. FIGS. 9 and
10 show a band-stop filter having an upper limit and a lower limit
defined for the attenuation frequency band, while FIGS. 11 and 12
show a low-pass filter having only the lower limit defined for the
attenuation frequency band, and either one of the filters is
defined depending on a purpose of use of the engine rotation speed
signal SNe. For example, in the case of detecting a rotational
fluctuation having a frequency higher than the resonance frequency,
the band-stop filter shown in FIGS. 9 and 10 is used. The reference
filter characteristic Fp is separately set for each of the engine
rotational drive portion 100 and the misfire/abnormal-noise
detecting portion 110, or the common reference filter
characteristic Fp may be used for the engine rotational drive
portion 100 and the misfire/abnormal-noise detecting portion 110.
For the misfire/abnormal-noise detecting portion 110, the reference
filter characteristic Fp may separately be defined for each of
misfire detection and abnormal noise detection.
At F1-3, any one of the rigidity values K1 to K3 stored in the
characteristic storage portion 94 is read. The rigidity values K1
to K3 to be read are determined depending on the input torque of
the damper device 26 and are determined in advance in relation to
the reference filter characteristic Fp. For example, in the engine
rotational drive portion 100 rotationally driving the engine 12,
the input torque of the damper device 26 is small, and therefore,
the rigidity value K1 is read. At F1-4, the actual resonance
frequency fr is calculated based on the rigidity values K1 to K3
and the inertia moment M in accordance with a map or an arithmetic
expression defined in advance. At F1-5, a frequency difference
.DELTA.fr between this actual resonance frequency fr and the set
resonance frequency fro is calculated, and at F1-6, the reference
filter characteristic Fp is corrected depending on the frequency
difference .DELTA.fr. Specifically, it is determined whether the
frequency difference .DELTA.fr is equal to or greater than a
predefined magnitude determination value .alpha., and if the
frequency difference .DELTA.fr is equal to or greater than the
magnitude determination value .alpha., as indicated by a broken
line in FIG. 9 or 11, the attenuation frequency band of the
reference filter characteristic Fp is corrected by an amount
corresponding to the frequency difference .DELTA.fr to move in a
deviation direction of the actual resonance frequency fr. If the
frequency difference .DELTA.fr is smaller than the predefined
magnitude determination value .alpha., as indicated by a broken
line in FIG. 10 or 12, the attenuation gain Go of the reference
filter characteristic Fp is increased and the attenuation frequency
band is narrowed to make an emphasis correction. This emphasis
correction is performed by increasing the attenuation gain Go in a
portion near the set resonance frequency fro and continuously
decreasing the attenuation gain Go in a frequency portion far from
the set resonance frequency fro. In the case of the low-pass filter
shown in FIG. 12, the maximum value of the attenuation gain Go may
be increased, and the attenuation gain Go may continuously be
decreased only on the lower limit side of the attenuation frequency
band as the frequency becomes further from the set resonance
frequency fro.
Subsequently, at F1-7, the engine rotation speed signal SNe is
read, and at F1-8, the read engine rotation speed signal SNe is
filtered in accordance with a corrected filter characteristic Fs
which is obtained after the reference filter characteristic Fp is
corrected at F1-6. As a result, the vibration of the engine
rotation speed signal SNe due to resonance caused depending on the
actual torsional rigidity of the damper device 26 is properly
attenuated. Specifically, for example, as shown in FIG. 5, when the
engine 12 is rotationally driven by the first motor generator MG1
to increase the engine rotation speed Ne, the rotational vibration
of the engine 12 occurs due to resonance of the damper device 26 in
the resonance frequency region, and therefore, the engine rotation
speed signal SNe also has rotational vibration as indicated by the
solid line; however, the signal SNe is filtered at F1-8 and the
movement of the signal SNe is thereby properly smoothed as
indicated by the broken line regardless of a variation in the
torsional rigidity and/or a temporal change of the damper device
26. At F1-9, the engine rotation speed signal SNe with the
rotational vibration reduced as described above is output and used
for the engine rotational drive by the engine rotational drive
portion 100 or the misfire detection or abnormal-noise detection by
the misfire/abnormal-noise detecting portion 110.
FIG. 13 is a flowchart for specifically explaining an engine
rotational drive control by the engine rotational drive portion 100
when the engine 12 is cranked and started by the first motor
generator MG1. At Q1-1, it is determined whether an engine rotation
request is supplied for cranking and starting the engine 12 by the
first motor generator MG1, and if the engine rotation request is
not supplied, the process is terminated, or if the engine rotation
request is supplied, Q1-2 and the subsequent steps are executed. At
Q1-2, the engine 12 is rotationally driven by the first motor
generator MG1. Specifically, if the hybrid vehicle 10 is in the
stop state, the first motor generator MG1 is rotated by the power
running torque in the positive rotation direction that is the
engine rotation direction, and the engine 12 can thereby
rotationally be driven in the positive direction. If the hybrid
vehicle 10 is in the running state, the first motor generator MG1
in the reverse rotation state is braked by applying a torque in the
positive rotation direction through the regenerative control etc.,
and the engine 12 can thereby rotationally be driven in the
positive rotation direction.
At Q1-3, the engine rotation speed signal SNe filtered by the
engine rotation filtering portion 104 is read, and at Q1-4, it is
determined whether the engine rotation speed Ne indicated by the
engine rotation speed signal SNe has reached a predefined
rotational drive termination determination value Ne1 through
starting control of the engine 12 including rotational drive,
ignition, fuel injection, etc. thereof. If the engine rotation
speed Ne has reached the rotational drive termination determination
value Ne1, Q1-5 is executed to terminate the rotational drive
(cranking) of the engine 12 by the first motor generator MG1. As a
result, the engine rotation speed Ne is promptly increased to the
rotational drive termination determination value Ne1 higher than
the resonance frequency band of the damper device 26, for example,
and is subsequently increased by self-rotation of the engine 12 due
to explosion to a predetermined target engine rotation speed such
as an idle rotation speed. At Q1-3, the filtering process of F1-7
to F1-9 of FIG. 8 may be executed. All the signal processes of F1-1
to F1-9 including the correction of the reference filter
characteristic may be executed at Q1-3.
As described above, when the engine 12 is rotationally driven for
cranking via the damper device 26 by the first motor generator MG1,
the engine rotation speed signal SNe after filtering is used for
determining whether the engine rotation speed Ne has reached the
rotational drive termination determination value Ne1, and
therefore, it can highly accurately be determined that the engine
rotation speed Ne has reached the rotational drive termination
determination value Ne1 without being influenced by engine rotation
vibration due to resonance of the damper device 26, so that the
cranking by the first motor generator MG1 can properly be
terminated when the engine rotation speed Ne has reached the
rotational drive termination determination value Ne1. Particularly,
since the engine rotation speed signal SNe supplied from the engine
rotation speed sensor 70 is filtered such that the vibration
component attributable to resonance is removed by the engine
rotation filtering portion 104 based on the actual resonance
frequency fr obtained by detecting the torsional rigidity (the
rigidity values K1 to K3) of the damper device 26, whether the
engine rotation speed Ne has reached the rotational drive
termination determination value Ne1 can always properly be
determined based on the engine rotation speed signal SNe with the
vibration component attributable to resonance properly removed
regardless of variations in the torsional rigidity due to
individual differences and temporal changes of the damper device
26.
FIG. 14 is a flowchart for specifically explaining a misfire
detection control and an abnormal noise detection control by the
misfire/abnormal-noise detecting portion 110. At Q2-1, it is
determined whether the engine 12 is in an operating state in which
the engine 12 rotates by itself due to explosion, and if the engine
12 is not in the operating state, the process is terminated, or if
the engine 12 is in the operating state, Q2-2 and the subsequent
steps are executed. At Q2-2, the engine rotation speed signal SNe
filtered by the engine rotation filtering portion 114 is read. At
Q2-2, the filtering process of F1-7 to F1-9 of FIG. 8 may be
executed. All the signal processes of F1-1 to F1-9 including the
correction of the reference filter characteristic may be executed
at Q2-2.
At Q2-3, it is determined whether the engine rotation speed signal
SNe includes a rotational fluctuation. If no rotational fluctuation
is included, i.e., if a rotational fluctuation amount .DELTA.SNe of
the engine rotation speed signal SNe is equal to or less than a
predefined presence/absence determination value .DELTA.SNe1, the
process is terminated, and if .DELTA.SNe>.DELTA.SNe1 is
satisfied, Q2-4 is executed. At Q2-4, it is determined whether the
rotational fluctuation amount .DELTA.SNe is large, i.e., whether
the rotational fluctuation amount .DELTA.SNe is equal to or greater
than a predefined misfire determination value .DELTA.SNe2, and if
.DELTA.SNe>.DELTA.SNe2 is satisfied, a misfire determination of
the engine 12 is made at Q2-5. If the engine 12 misfires, the
explosion becomes irregular and generates a rotational fluctuation
having a period and a magnitude different from a rotational
fluctuation resulting from normal explosion, and therefore, the
misfire of the engine 12 can be determined based on the rotational
fluctuation amount .DELTA.SNe. In this case, the misfire of the
engine 12 can be suppressed by changing the torque Te or the engine
rotation speed Ne of the engine 12, for example.
On the other hand, if the determination of Q2-4 is NO (negative),
i.e., if the rotational fluctuation amount .DELTA.SNe is small and
.DELTA.SNe<.DELTA.SNe2 is satisfied, Q2-6 is executed to make an
abnormal noise determination. If inter-cylinder torque variations
etc. of the engine 12 cause a rotational vibration having a period
and a magnitude different from a rotational vibration resulting
from normal explosion, an abnormal noise (tapping phenomenon) such
as a tooth contact sound may occur in a gear meshing portion of the
power transmission path, and therefore, the abnormal noise
determination can be made based on the rotational fluctuation
amount .DELTA.SNe. In this case, for example, by changing the
torque Te or the engine rotation speed Ne of the engine 12, the
rotational fluctuation of the engine rotation speed Ne can be
reduced to suppress the occurrence of the abnormal noise.
As described above, the misfire determination and the abnormal
noise determination of the engine 12 are made during the operation
of the engine 12 based on the rotational fluctuation of the engine
rotation speed signal SNe after filtering, so that the misfire
determination and the abnormal noise determination can properly be
made with high accuracy without being affected by engine rotational
vibration due to resonance of the damper device 26. Particularly,
since the engine rotation speed signal SNe supplied from the engine
rotation speed sensor 70 is filtered such that the vibration
component attributable to resonance is removed by the engine
rotation filtering portion 114 based on the actual resonance
frequency fr obtained by detecting the torsional rigidity (the
rigidity values K1 to K3) of the damper device 26, the misfire
determination and the abnormal noise determination are always
properly made based on the engine rotation speed signal SNe with
the vibration component attributable to resonance properly removed
regardless of variations in the torsional rigidity due to
individual differences and temporal changes of the damper device
26.
As described above, in the hybrid vehicle 10 of this example, the
torsional rigidity (such as the rigidity value K1) is detected by
applying the torque Tin to the damper device 26 through the power
running control of the first motor generator MG1 to measure the
twist angle .PHI. while the rotation of the crankshaft 24 is locked
by the meshing brake 36, and the actual resonance frequency fr is
calculated based on the detected torsional rigidity. Therefore, the
actual resonance frequency fr can properly be calculated based on
the actual torsional rigidity regardless of variations in torsional
rigidity due to individual differences etc. and temporal changes of
the damper device 26. The filtering is then performed to attenuate
the vibration component of the actual resonance frequency fr in the
engine rotation speed signal SNe supplied from the engine rotation
speed sensor 70, so that the vibration component attributable to
resonance is properly reduced in the obtained engine rotation speed
signal SNe, and the subsequent controls using the engine rotation
speed signal SNe, or specifically, the rotational drive control of
the engine 12 by the engine rotational drive portion 100 and/or the
misfire and abnormal noise determinations by the
misfire/abnormal-noise detecting portion 110 are properly
performed.
In the filtering of the engine rotation speed signal SNe, a
correction is made based on the frequency difference .DELTA.fr
between the actual resonance frequency fr and the set resonance
frequency fro for the reference filter characteristic Fp having the
attenuation frequency band and the attenuation gain Go defined in
advance depending on the set resonance frequency fro, and the
engine rotation speed signal SNe is filtered in accordance with the
corrected filter characteristic Fs which is obtained after the
correction, so that the vibration component attributable to
resonance is properly reduced.
If the frequency difference .DELTA.fr between the actual resonance
frequency fr and the set resonance frequency fro is large, the
attenuation frequency band of the reference filter characteristic
Fp is corrected to move in the deviation direction of the resonance
frequency, so that the vibration component attributable to
resonance is properly reduced from the engine rotation speed signal
SNe even if the frequency difference .DELTA.fr is large. On the
other hand, if the frequency difference .DELTA.fr between the
actual resonance frequency fr and the set resonance frequency fro
is small, the attenuation gain Go of the reference filter
characteristic Fp is increased and the attenuation frequency band
is narrowed to make an emphasis correction, and therefore, only the
vibration component attributable to resonance can more properly be
reduced from the engine rotation speed signal SNe.
Another example of the present invention will be described. In the
following example, portions substantially the same as those in the
example are denoted by the same reference numerals and will not be
described in detail.
FIG. 15 is a skeleton diagram for explaining a drive system of a
hybrid vehicle 200 to which the present invention is applied,
showing main portions of the control system together and
corresponding to FIG. 1. The hybrid vehicle 200 is different from
the hybrid vehicle 10 of the above example in an engine rotational
drive portion 210 in an engine-related control portion 204
functionally included in an electronic control device 202. The
engine rotational drive portion 210 rotationally drives the engine
12 with the first motor generator MG1 and functionally includes a
fluctuation characteristic correcting portion 212 and an electric
motor rotational fluctuation imparting portion 214 so as to
suppress the rotational vibration itself of the engine 12 caused by
the actual resonance frequency fr of the damper device 26. The
electric motor rotational fluctuation imparting portion 214 imparts
a periodic fluctuation to a target rotation speed Nmg1t of the
first motor generator MG1 depending on the actual resonance
frequency fr of the damper device 26 so as to suppress the
rotational vibration of the engine 12, and the fluctuation
characteristic correcting portion 212 sets a fluctuation
characteristic related to an amplitude and a fluctuation frequency
band of the periodic fluctuation depending on the actual resonance
frequency fr of the damper device 26.
FIG. 16 is a flowchart for specifically explaining a signal process
by the fluctuation characteristic correcting portion 212. At F2-1
of FIG. 16, similarly to F1-1 of FIG. 8, the inertia moment M
necessary for calculating the actual resonance frequency fr of the
damper device 26 is read. At F2-2, an initially-set reference
fluctuation characteristic Wp is read. The reference fluctuation
characteristic Wp is a characteristic for imparting to the MG1
target rotation speed Nmg1t a rotational fluctuation opposite in
phase to the rotational vibration of the engine 12 caused by the
resonance of the damper device 26, is set based on the set
resonance frequency fro defined in advance, and is defined as
indicated by solid lines in FIGS. 17 and 18 in terms of a
fluctuation frequency band defined to include the set resonance
frequency fro and an amplitude Ao within the fluctuation frequency
band.
At F2-3, the rigidity value K1 stored in the characteristic storage
portion 94 is read. The reference fluctuation characteristic Wp is
set based on the rigidity value K1 (which is an initially-set
value) in a region of a small input torque. At F2-4, similarly to
F1-4, the actual resonance frequency fr is calculated based on the
rigidity value K1 and the inertia moment M in accordance with a map
or an arithmetic expression defined in advance. At F2-5, similarly
to F1-5, the frequency difference .DELTA.fr between the actual
resonance frequency fr and the set resonance frequency fro is
calculated, and at F2-6, the reference fluctuation characteristic
Wp is corrected depending on the frequency difference .DELTA.fr.
Specifically, it is determined whether the frequency difference
.DELTA.fr is equal to or greater than a predefined magnitude
determination value .beta., and if the frequency difference
.DELTA.fr is equal to or greater than the magnitude determination
value .beta., as indicated by a broken line in FIG. 17, the
fluctuation frequency band of the reference fluctuation
characteristic Wp is corrected by an amount corresponding to the
frequency difference .DELTA.fr to move in a deviation direction of
the actual resonance frequency fr. If the frequency difference
.DELTA.fr is smaller than the predefined magnitude determination
value .beta., as indicated by a broken line in FIG. 18, the
amplitude Ao of the reference fluctuation characteristic Wp is
increased and the fluctuation frequency band is narrowed to make an
emphasis correction. This emphasis correction is performed by
increasing the amplitude Ao in a portion near the set resonance
frequency fro and continuously decreasing the amplitude Ao in a
frequency portion far from the set resonance frequency fro. The
magnitude determination value .beta. may be the same as the
magnitude determination value .alpha. or may be defined as a
different value.
By imparting a rotational fluctuation having an opposite phase to
rotational vibration of the engine 12 to the target rotation speed
Nmg1t of the first motor generator MG1 in accordance with a
fluctuation characteristic Ws after the correction as described
above, the periodical change of the engine rotation speed Ne due to
resonance caused depending on the torsional rigidity of the damper
device 26 is properly suppressed regardless of variations in the
actual torsional rigidity of the damper device 26 when the engine
12 is rotationally driven by the first motor generator MG1. FIG. 19
is a flowchart for specifically explaining an engine rotational
drive control by the engine rotational drive portion 210 when the
engine 12 is cranked and started by the first motor generator MG1,
wherein the engine rotational drive control includes a control of
imparting the rotational fluctuation to the target rotation speed
Nmg1t in accordance with the corrected fluctuation characteristic
Ws by the electric motor rotational fluctuation imparting portion
214. Q3-2 and Q3-3 of FIG. 19 correspond to the electric motor
rotational fluctuation imparting portion 214.
At Q3-1 of FIG. 19, it is determined whether an engine rotation
request is supplied for cranking and starting the engine 12 by the
first motor generator MG1, and if the engine rotation request is
not supplied, the process is terminated, or if the engine rotation
request is supplied, Q3-2 and the subsequent steps are executed. At
Q3-2 to Q3-4, the engine 12 is rotationally driven (cranked) by the
first motor generator MG1 to start the engine 12. Specifically, if
the hybrid vehicle 200 is in the stop state, the first motor
generator MG1 is rotated by the power running torque in the
positive rotation direction that is the engine rotation direction,
and the engine 12 can thereby rotationally be driven in the
positive direction. If the hybrid vehicle 200 is in the running
state, the first motor generator MG1 in the reverse rotation state
is braked by applying a torque in the positive rotation direction
through the regenerative control etc., and the engine 12 can
thereby rotationally be driven in the positive rotation direction.
In this case, in this example, the MG1 target rotation speed Nmg1t
is read at Q3-2, and a rotational fluctuation is imparted at Q3-3
to the MG1 target rotation speed Nmg1t in accordance with the
corrected fluctuation characteristic Ws corrected by the
fluctuation characteristic correcting portion 212. At Q3-4, the MG1
target rotation speed Nmg1t with the rotational fluctuation
imparted is output, and the first motor generator MG1 is operated
in accordance with the MG1 target rotation speed Nmg1t to
rotationally drive the engine 12. At Q3-3, the reference
fluctuation characteristic correction process of F2-1 to F2-6 of
FIG. 16 may be performed.
As described above, by imparting a rotational fluctuation to the
MG1 target rotation speed Nmg1t in accordance with the corrected
fluctuation characteristic Ws determined depending on the actual
torsional rigidity of the damper device 26, the periodic change of
the engine rotation speed Ne due to resonance caused depending on
the torsional rigidity of the damper device 26 can be suppressed
(canceled out) regardless of the variation in torsional rigidity of
the damper device 26. The phase of the rotational fluctuation
imparted to the MG1 target rotation speed Nmg1t is adjusted based
on, for example, the engine rotation speed signal SNe supplied from
the engine rotation speed sensor 70 such that the fluctuation of
the engine rotation speed Ne due to resonance is reduced. FIG. 20
is an example of a time chart showing changes in the MG1 target
rotation speed Nmg1t, the MG1 rotation speed Nmg1, and the engine
rotation speed Ne when the rotational fluctuation is imparted to
the MG1 target rotation speed Nmg1t in accordance with the
corrected fluctuation characteristic Ws in this way, and as
indicated by a broken line of FIG. 20, when the engine 12 is
rotationally driven by the first motor generator MG1 with the MG1
target rotation speed Nmg1t without rotational fluctuation, the
engine rotation speed Ne and the engine rotation speed signal SNe
periodically change due to resonance. In contrast, in this example,
a periodic fluctuation opposite in phase to the periodic change of
the engine rotation speed Ne is imparted to the MG1 target rotation
speed Nmg1t in accordance with the corrected fluctuation
characteristic Ws, so that the periodic change of the engine
rotation speed Ne due to resonance is offset as indicated by a
solid line of FIG. 20, and the engine rotation speed Ne is smoothly
increased regardless of the resonance of the damper device 26. The
engine rotation speed signal SNe supplied from the engine rotation
speed sensor 70 also smoothly changes similarly to the engine
rotation speed Ne.
Returning to FIG. 19, at Q3-5, the engine rotation speed signal SNe
supplied from the engine rotation speed sensor 70 is read, and at
Q3-6, it is determined whether the engine rotation speed Ne
indicated by the engine rotation speed signal SNe has reached the
predefined rotational drive termination determination value Ne1
through the starting control of the engine 12 including rotational
drive, ignition, fuel injection, etc. If the engine rotation speed
Ne indicated by the engine rotation speed signal SNe has reached
the rotational drive termination determination value Ne1, Q3-7 is
executed to terminate the rotational drive (cranking) of the engine
12 by the first motor generator MG1. As a result, the engine
rotation speed Ne is promptly increased to the rotational drive
termination determination value Ne1 higher than the resonance
frequency band of the damper device 26, for example, and is
subsequently increased by the self-rotation due to explosion to a
predetermined target engine rotation speed such as an idle rotation
speed.
As described above, when the engine 12 is rotationally driven for
cranking via the damper device 26 by the first motor generator MG1,
the MG1 target rotation speed Nmg1t is periodically fluctuated
depending on the actual resonance frequency fr to suppress the
rotational vibration of the engine 12 caused by the torsional
rigidity of the damper device 26, so that the rotational vibration
itself of the engine rotation speed Ne due to the resonance is
suppressed, and therefore, the vibration component attributable to
the resonance is properly reduced in the obtained engine rotation
speed signal SNe. As a result, it can highly accurately be
determined that the engine rotation speed Ne has reached the
rotational drive termination determination value Ne1 based on the
engine rotation speed signal SNe, and when the engine rotation
speed Ne reaches the rotational drive termination determination
value Ne1, the cranking by the first motor generator MG1 can
properly be terminated. Particularly, since the fluctuation
characteristic (the corrected fluctuation characteristic Ws) of the
rotational fluctuation imparted to the MG1 target rotation speed
Nmg1t is determined based on the actual resonance frequency fr
obtained by detecting the torsional rigidity (the rigidity value
K1) of the damper device 26, the periodical change of the engine
rotation speed Ne due to resonance is properly suppressed
regardless of variations in torsional rigidity due to individual
differences and temporal changes of the damper device 26, and
whether the engine rotation speed Ne has reached the rotational
drive termination determination value Ne1 can always properly be
determined with high accuracy based on the engine rotation speed
signal SNe supplied from the engine rotation speed sensor 70
detecting the engine rotation speed Ne.
Further, the torsional rigidity (such as the rigidity value K1) is
detected by applying the torque Tin to the damper device 26 through
the power running control of the first motor generator MG1 to
measure the twist angle 1 while the rotation of the crankshaft 24
is locked by the meshing brake 36, and the actual resonance
frequency fr is calculated based on the detected torsional
rigidity, so that the actual resonance frequency fr can be properly
calculated based on the actual torsional rigidity regardless of
variations and temporal changes of the rotational characteristics
due to an individual difference etc. of the damper device 26.
Regarding the fluctuation characteristic of the periodic
fluctuation for the MG1 target rotation speed Nmg1t, a correction
is made based on the frequency difference .DELTA.fr between the
actual resonance frequency fr and the set resonance frequency fro
for the reference fluctuation characteristic Wp having the
amplitude Ao and the fluctuation frequency band defined in advance
depending on the set resonance frequency fro, and the MG1 target
rotation speed Nmg1t is periodically fluctuated in accordance with
the fluctuation characteristic Ws after the correction, so that the
rotational vibration itself of the engine rotation speed Ne due to
resonance is properly suppressed, and the vibration component
attributable to the resonance is properly reduced in the obtained
engine rotation speed signal SNe.
If the frequency difference .DELTA.fr between the actual resonance
frequency fr and the set resonance frequency fro is relatively
large, the fluctuation frequency band of the reference fluctuation
characteristic Wp is corrected to move in the deviation direction
of the resonance frequency, so that the rotational vibration of the
engine rotation speed Ne due to resonance is properly suppressed
even if the frequency difference .DELTA.fr is large. On the other
hand, if the frequency difference .DELTA.fr between the actual
resonance frequency fr and the set resonance frequency fro is
small, the amplitude Ao of the reference fluctuation characteristic
Wp is increased and the fluctuation frequency band is narrowed to
make an emphasis correction, and therefore, the rotational
vibration of the engine rotation speed Ne due to resonance as well
as the vibration of the engine rotation speed signal SNe can more
properly be reduced.
Although the examples of the present invention have been described
in detail with reference to the drawings, these are merely an
embodiment and the present invention can be implemented in
variously modified and improved forms based on the knowledge of
those skilled in the art.
REFERENCE SIGNS LIST
10, 200: hybrid vehicle (vehicle) 12: engine 14: driving wheel 26:
damper device (rotating member) 26a: first rotating element
(coupling portion on the engine side) 36: meshing brake (rotation
lock mechanism) 70: engine rotation speed sensor 90, 202:
electronic control device (vehicle control device) 92:
characteristic learning portion (characteristic detecting portion)
100: engine rotational drive portion 102, 112: filter correcting
portion 104, 114: engine rotation filtering portion 110:
misfire/abnormal-noise detecting portion (misfire detecting
portion, abnormal-noise detecting portion) 210: engine rotational
drive portion 212: fluctuation characteristic correcting portion
214: electric motor rotational fluctuation imparting portion MG1:
first motor generator (electric motor) Tin: input torque .PHI.:
twist angle K1, K2, K3: rigidity value (rotational characteristic,
torsional rigidity) Ne: engine rotation speed SNe: engine rotation
speed signal Nmg1t: MG1 target rotation speed (target rotation
speed of the electric motor) fr: actual resonance frequency fro:
set resonance frequency .DELTA.fr: frequency difference between the
actual resonance frequency and the set resonance frequency Fp:
reference filter characteristic Fs: corrected filter characteristic
Wp: reference fluctuation characteristic Ws: corrected fluctuation
characteristic
* * * * *